These were my three posts from gamefaqs - if you don't mind opening up your ps3, this may fix your ps3:
I believe your blu-ray lens has some dust on it. Try a regular DVD movie to see if that works fine, as there are separate lenses for DVDs and blu-rays. If regular DVDs play fine, you need to get inside the drive and clean the smaller of the two lenses. I've tried one of those discs with the microfiber bristles, but they don't work for me. If you have a Slim, there are four security torx head screws you'll have to drill out in order to get the cover off, unless you happen to have the correct tool. Once that's done, there are a couple of small phillips head screws on the drive. You'll have to bend the crap out of the sheet metal cover in order to see the lenses - make sure you don't upset the plastic pieces in the top of the cover, as these need to stay in place. I was barely able to get a fingertip all the way back on to the blu-ray lens and wipe it clean - a q-tip may help, but it may leave some cotton on the lens. Doing this beats the hell out of getting a new ps3 and losing copyrighted data. Even if you have PSN+ and have cloud saves for copyright protected saves, you'll still lose any movies/TV episodes you downloaded, and you cannot download them without paying for them again. Hope this helps!
omglol - 30 seconds after the above post, I put in the blu-ray for the 2003 Galactica mini-series, and it froze. My landlord recently did a lot of spackling/painting in my apartment, so I knew this was coming. I popped the plastic cover off (I don't even keep the screws in), and there are three screws for the sheet metal cover. I bent that back so that it was sitting vertical. You can now see all of the levers that guide the disc in, and the hub that holds it in place. There are two small phillips head screws at the very front part of the drive housing that connect the top plastic half to the bottom half. After they're out, you can hold the top half open about 30º and get to the lenses. The blu-ray drive is performing perfectly once again. Too funny, the timing.
When you're able to connect a new ps3 to your old one with an ethernet cable, everything gets copied over, including copyrighted saves and movies. With your buddy's fat ps3, it is easier to get into the blu-ray drive, but he has to be careful about two things. There's a small cable with a micro-connector on the left side of the drive, and a ribbon cable on the underside of the drive. He'll have to make sure that the micro-connector is not damaged when he plugs it back in, and ensure that the ribbon cable is properly oriented when he reconnects it. IIRC, it is easier to upset the plastic levers on those old style drives.